Symptoms and Prevention of Potato Dry Rhizoctonia
Symptoms mainly affect young shoots, stem bases and tubers. Some buds infected and rot before excavation form bud rot, resulting in lack of seedlings. After unearthed, the lower leaves of the infected plants were yellowed, and the stem base formed brown depression spots, and the size was 1 to 6 cm. On the lesions or base of the stem often covered with a layer of purple mycelium, sometimes the stem base and tubers give birth to different sizes (1 - 5mm) of the shape of the block or sheet, scattered or aggregate of small sclerotia; mild disease The symptoms of the strain are not obvious, and serious diseased plants can form litter or wilting on the top or leaf curl. The pathogen Rhizoctonia solani Ktihn is known as Rhizoctonia solani, a fungus belonging to the genus Deuteromycotina. The primary mycelium is colorless and has a diameter of 4.98-8.71 um. The branches are at right angles or near right angles. The branches are more contracted and have 1 diaphragm. The new branch mycelium gradually turns brown, and becomes thick and short and then becomes sclerotia. . The sclerotia are white at first, and then become light brown or dark brown with a size of 0.5-5 mm. The lowest temperature of mycelial growth was 4°C, the highest was 32-33°C, the optimum was 23°C, and the growth was stopped at 34°C. The sclerotia had a suitable temperature of 23-28°C.
The route of transmission and onset of disease wintered in sclerotia on sick potatoes or in soil books. The diseased seed potato is the source of infestation early in the year and is also far
The main route to spread. The occurrence of the disease is related to the cold and humid conditions in the spring. The incidence of early onset or low soil temperature after sowing is heavy. The bacteria can infect peas in addition to infesting potatoes.
Control methods (1) Selection of disease-resistant varieties, such as Genghui, plateau system, and Shengli No. 1, are more resistant to disease. (2) Establish a disease-free farmland and sow disease-free potatoes. (3) In regions where the incidence is heavy, especially in high-altitude cold mountain areas, special attention should be paid to proper sowing and avoiding early sowing. (4) Before sowing, use 50% carbendazim WP 500 times solution or 50% thiram WP 1000 times soak for 10 minutes. (5) See mungbean blight for other methods.
Rushan Jinguo Food Co., Ltd , https://www.jinguofood.cn